Perineural involvement by benign prostatic glands on needle biopsy

Area of Science:

• Pathology
• Urology
• Oncology

Background:

• Benign perineural involvement, where benign prostatic glands appear in the perineural space, is an uncommon finding.
• This phenomenon has not been extensively studied in the context of prostate needle biopsies, leading to potential diagnostic challenges.

Purpose of the Study:

• To evaluate the patterns and diagnostic implications of benign perineural involvement observed in prostate needle biopsies.
• To identify features that may mimic malignancy and to assess the utility of immunohistochemistry in differentiating benign from malignant perineural invasion.

Main Methods:

• Retrospective review of 27 prostate needle biopsy cases exhibiting perineural involvement.
• Analysis of morphological patterns (indentation, tracking, wrapping, intraneural, adjacent) and gland atrophy.
• Immunohistochemical staining for high molecular weight cytokeratin (HMWCK) and p63 on selected cases.

Main Results:

• Various patterns of benign perineural involvement were observed, with indentation being the most common (51.8%).
• Glandular atrophy was present in a significant proportion of cases (61.4%).
• Immunohistochemistry showed mixed results, with HMWCK and p63 being positive in 75% of cases with available tissue, but negative in cases with partial atrophy, highlighting diagnostic difficulty.

Conclusions:

• Benign perineural involvement, particularly intraneural patterns and incomplete encirclement, can closely mimic perineural invasion by cancer.
• Diagnostic challenges arise, especially when basal cells are not identifiable on H&E or when immunohistochemistry is negative.
• Careful evaluation of H&E morphology and comparison with adjacent benign glands are essential for accurate diagnosis.